Ms. De Los Rios

1

Earths Structure and Materials- Course 2
3.2 Convection and the Mantle

• Ms. De Los Rios
• 7th Grade Science
• CGPA

2
Vocabulary 3.2

• Radiation- The transfer of energy by
  electromagnetic waves.
• Convection- The transfer of heat by the movement
  of a fluid.
• Conduction- The transfer of heat from one
  particle of matter to anther.
• Convection Current- The movement of fluid, caused
  by differences in temp. that transfers heat from
  one part of the fluid to another.
• Density- The ratio of the mass of a substance to
  its volume
• (mass/volume)

3
My Planet Diary- Lighting Up the Subject pg. 106

• Misconception Rock cannot flow.
• Did you know that the solid rock in Earths
  mantle can flow like a fluid?
• To learn how, look at this image of a lava lamp.
  
• Heat from a bulb causes solid globs of wax at
  the bottom of the lamp to expand. As they expand,
  the globs become less dense. The globs then rise
  through the more dense fluid that surrounds
  them. In Earths mantle, great heat and pressure
  create regions of rock that are less dense than
  the rock around them. Over millions of years,
  the less dense rock slowly riseslike the solid
  globs in the lava lamp!

4
My Planet Diary- Lighting Up the Subject pg. 106

• Compare and Contrast
• Think about your own observations of liquids that
  
• flow. How is flowing rock different from flowing
• water?
• __________________________________________________
  __________________________________________________
  __________________________________________________
  __________________________________________________
  ____

5
How is Heat Transferred?

• Heat is constantly being transferred inside Earth
  and all around Earths surface.
• What is heat transfer????
• The movement of energy from a warmer object to a
  cooler object.
• Three types of heat transfer
• radiation, convection, and conduction.
• The transfer of energy that is carried in rays
  like light is called radiation.
• Heat transfer by the movement of a fluid is
  called convection.
• Heat transfer between materials that are touching
  is called conduction.

6
Radiation

• The sun constantly transfers light and heat
  through the air, warming your skin. The transfer
  of energy that is carried in rays like light is
  called radiation.
• Examples of radiation
• ___________________________
• ___________________________
• ___________________________
• ___________________________

7
Conduction

• Have you ever walked barefoot over hot sand? Your
  feet can feel as if they are burning! That is
  because the sand transfers its heat to your skin.
  Heat transfer between materials that are touching
  is called conduction.
• Examples of Conduction
• _____________________________
• _____________________________
• _____________________________
• _____________________________

8
Convection

• Seagulls often soar on warm air currents. The
  currents are created as warm air rises from the
  ground The warm air heats cooler air above it
  Heat transfer by the movement of a fluid is
  called convection.
• Examples of Convection
• ________________________
• ________________________
• ________________________
• ________________________

9
Assess Your Understanding pg. 107

• I get it! Now I know that the three types of heat
  transfer are
• __________________________________________________
  __________________________________________________
  __________________________________________________
  ______

10
How Does Convection Occur in Earths Mantle? Pg.
108

• Density is a measure of how much mass there is in
  a given volume of a substance.
• The flow that transfers heat within a fluid is
  called a convection current.
• Three Processes/forces combine to set
  convection in motion
• Heating and cooling of a fluid,
• changes in the fluids density,
• force of gravity combine to set convection
  currents in motion.
• Inside Earth, large amounts of heat are
  transferred by convection currents within the
  core and mantle.
• Heat from the core and the mantle causes
  convection currents in the mantle.

11
How Does Convection Occur in Earths Mantle? Pg.
108

• Convection Currents
• What is Density?
• Density is a measure of how much mass there is in
  a given volume of a substance.
• The flow that transfers heat within a fluid is
  called a convection current.

12
Convection Currents pg. 108

• -Heating and cooling of a fluid
• Changes in the fluids density AND
• The force of gravity
• ALL Combine to set convection currents in motion!
• Inside Earth, large amounts of heat are
  transferred by convection currents within the
  core and mantle.
• Heat from the core and the mantle itself causes
  convection currents in the mantle.

13
Convection Currents in Earth pg. 109

• Over millions of years, the great heat and
  pressure in the mantle have caused solid mantle
  rock to warm and flow very slowly.
• Many geologists think that plumes of mantle rock
  rise slowly from the bottom of the mantle toward
  the top.
• The hot rock eventually cools and sinks back
  through the mantle.
• Over and over, the cycle of rising and sinking
  takes place.
• Convections currents like these have been moving
  inside Earth for more than four billion years!

14
Did You Know?

• Convection currents may form on planets other
  than Earth. For example, scientists believe that
  the Great Red Spot on Jupiter may be the result
  of storms that have convection currents.

15
Apply It! Pg. 108

• Hot springs are common in Yellowstone National
  Park. Here, melted snow and rain-water seep to a
  depth of 3,000 meters, where a shallow magma
  chamber heats the rock of Earths crust. The rock
  heats the water to over 200C and keeps it under
  very high pressure.
• Compare and Contrast The heated
• Water is (more / less) dense than the
• melted snow and rainwater.
• 2. Challenge What might cause
• convection currents in a hot spring?
• The heated water rises to the surface.
• As it rises, it cools, becomes more dense, sinks
• Back down to the hot rocks, and is reheated.

16
Convection and the Mantle- Art in Motion pg. 109
Mantle Convection Heat from the core and the
mantle itself causes convection currents in the
mantle. Describe the hot, convecting Mantle by
placing the following words in the boxes For
points A and B.
hotter
Less dense
rises
colder
More dense
sinks
17
Assess Your Understanding pg. 109

• 1a. Explain A convection current transfers (heat
  / air) within a fluid.
• b. Infer in which parts of Earths core do
  convection currents occur?
• _______________________________________________
• c. Predict What would happen to the convection
  currents in the mantle if Earths interior
  eventually cooled down? Why?
• __________________________________________________
  __________________________________________________
  __
• I get it! Now I know that convection currents in
  the mantle are caused by _________________________
  _________________.